Aluminum alloys having a high static and dynamic bearing capacity include the alloys AA 2014 and AA 2214. Drop-forged parts for wheel and brake systems of airplanes are manufactured from these Al alloys in the artificially aged state. The semi-finished products produced from the alloy intrinsically have the listed strength properties of the alloys, especially at lower temperatures. However, at temperatures of more than 100° C. these properties decrease more rapidly than is the case with alloys of the group AA 2618.
Semi-finished products of the alloys of group AA 2618 have better high-temperature stability and are utilized for a variety of uses such as compressor impellers for rechargeable diesel engines or for rotors of ultracentrifuges. However, at temperatures below 100° C., the aluminum alloys of the group AA 2014 and AA 2214 have greater bearing capacity.
In the wheel brake system of airplanes considerable heat is generated during the braking process. This leads to temperature increases even in the wheels, which typically are fabricated of an AA 2014 or AA 2214 alloy. These can cause early overageing of this alloy and lead to a severe limitation of the service life of the structural part.
In compressor impellers the transition to titanium alloys has been made to give the compressor impellers the necessary static and dynamic strength properties even at increased temperatures. However, employing titanium is expensive is therefore not suitable for the production of airplane wheels. Furthermore, titanium is less well suited as a material for wheels due to its limited thermal conductivity.
The problematic described above is not new. Therefore, for many years there has been the wish for an Al alloy, which combines the high strength properties of the alloys AA 2014 or AA 2214 at ambient temperature and the thermal stability of the alloys AA 2618 or 2618 A.